Microfabrication of high aspect ratio BST pillar arrays by epoxy gel casting from aqueous suspensions with added water soluble epoxy resin

The present paper reports on the successful fabrication of micro-sized pillar arrays of Ba0.6Sr0.4TiO3 (BST) electroceramics via cost effective epoxy gel casting (EGC) consolidation method based on the in situ polymerization of aqueous suspensions with added water soluble epoxy resin. The synthesized BST solid solution powder was fine milled and surface protected against hydrolysis to avoid its degradation in the aqueous environment. The micro patterning process was divided in the following steps: (i) production of high quality SU-8 master moulds by photolithography and of the respective negative replicas in PDMS (soft mould); (ii) casting of stable high solid loading BST suspensions in the soft moulds with added setting agents followed by de-moulding, drying and sintering. Patterned array of hexagonal shaped pillars with 320 μm of height and side length ∼40 μm were obtained with smooth side wall features along height. Various structural, mechanical and electrical properties of BST material after sintering were also measured to demonstrate the feasibility of the proposed aqueous processing route.